Closes#1525
* Adds validation for the `Content-MD5` header.
* If the header value is invalid, the gateway now returns an `InvalidDigest` error.
* If the value is valid but does not match the payload, it returns a `BadDigest` error.
* Adds integration test cases for `PutBucketCors` with `Content-MD5`.
Fixes#457. There are some buggy clients that include headers not
actually set on the request in the signed headers list. For these
we need to include them in the signature canoncal string with
empty values.
This fixes the case where clients can include the content-length
header in the signed headers for a 0 length file (like s3cmd).
Since we had to hoist the aws code into versitygw, we can also
remove the hack for the "User-Agent" header in the hard coded
excludes list and just remove it from the excludes list.
This is a hack to replace the ignored headers in the aws-sdk-go-v2
internal/v4 package. The headers in the default ignore list include
User-Agent, but this is included is signed headers from some clients.
fixes#396
This change removes all spaces after the algorithm to have
standard parsing for the following key/value pairs. This fixes
some clients that were using a slightly different format than
the example AWS request strings.
